Answer
$\approx0.4$ seconds
Work Step by Step
The ball lands on the opposite side when $h=0$. So using the given formula with $h_0=9$ and $v_0=-16$ we get: $0=-16t^2-16t+9$
Then using the quadratic formula: $t=\frac{16\pm\sqrt{(-16)^2-4(-16)9}}{2(-16)}=\frac{-2\pm\sqrt{13}}{4}$
We consider only the positive answer:
$t=\frac{2+\sqrt{13}}{4}\approx0.4$
